1. Field of the Invention
The present invention relates to a light emitting diode, more specifically, to a light emitting diode capable of scattering widely and efficiently emitted light.
2. Description of the Prior Art
Generally, a light emitting diode for emitting light by a current is well known.
A conventional typical light emitting diode 1 is shown in FIG. 5. The light emitting diode 1 comprises a substrate 2, a pair of electrodes 3a and 3b mounted on the substrate 2, a light emitting element 4 fixed on the substrate 2, bonding wires 5 for connecting the light emitting element 4 with the electrodes 3a and 3b and a resinous cover 6 mounted on the substrate to seal the light emitting element 4 and bonding wires 5.
The cover 6 acts to prevent the light emitting element 4 and bonding wires 5 from corroding and so on, and is formed from a transparent epoxy resin material to pass through light emitted from the light emitting element 4.
In the aforementioned conventional light emitting diode 1, a large number of light scattering micro particles 7 of SiO2, TiO2 and so on are mixed in the cover 6 in order to scatter widely light from the light emitting element 4 and to enhance brightness of the light by diffused reflection of the light within the cover 6 (see Japanese Laid-Open Publication 2000-124507). In this way, the light radiated from the light emitting element 4 strikes against the light scattering particles 7 to go to any directions within the cover 6 while repeating the reflection or refraction, thus scattering from outer surfaces of the cover 6.
However, since the light scattering particles mixed into the cover 6 are minute in the construction as described above, when the light strikes against the particles, the refraction of the light by the particles is less.
Consequently, it is not possible to obtain a large scattering effect of light. In fact, when viewing a light emitting projected surface 8 of the light emitting element 4 from the right above thereof (direction of arrow A) in FIG. 5, the light emitting projected surface 8 can be looked to shine brightly, while, the brightness of the light emitting projected surface is less than that in the case of viewing the projected surface from the right above, when viewing obliquely slightly the light emitting projected surface 8.
As a result, there is a problem that the light emission is not uniform in accordance with an angle of viewing the light emitting projected surface.
Further, if amount of the light scattering particles mixed into the cover is more, it is possible to obtain a high light scattering effect, while the light transmission is less to thus become low brightness. Inversely, if the amount of mixing the particles 7 is less, it is not possible to obtain sufficient light scattering effect. Consequently, there is a problem that more producing processes and a high cost for production are required since the mixed amount of the particles must be precisely adjusted based on a kind and a size of the light emitting diode.